The economy of the animal kingdom, considered anatomically, physically, and philosophically

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Orderly arrangement, that their apparent irregularity is never- tholess in relation to tho disserunt modos of action, in itsolsmost perfectly regular. Thus do the two Outermost membranoson ly contributo to tho perfection of the third, and oti this account successively disper With the disserendo of tho blood enclosed in the motive rings. A similar las holds in rogardio the tendinous membrano montioned by Heister n. I 20),

as that os iis actuating fluid and fit si principio, and thereby is

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more perfeci: and we shali then spe, Whethor in the course Os our in Vestigation, Osrocis in generat indicate this to be a genuine membrane; lar since autopsy cannot determine the question, We must come to our conclusion by induction alone su. 10, 16).143. Au these membranes tasten collectively, and connected by mutuat Superposition, inclose and convey the red blood. Thisis a faci, Which, as it is attested by nil the learned, is un- doubted. The smallor vesseis, Which forWard tho blood of the Same Order ns themselves, or the red blood, appear to consistos as many integuments as the larger, but With a disseretice Recording to the muscular coat, Whicli, Where it is adornest Withsseshy fibres, has also a superstructure formed of the vascularand cellular subsidiary membranos; but Where it consists of fibresor motive rings, Whicli are White, or belonging to the pellucidbl00d n. 142), is distinguished by other succenturiate, auXilinryphilyrae, the ossice of Whicli consisis in carrying down the more simple blo d. This is the reason for Which When there is acessation os seshy substance in the rings of the larger vesset, the cellular tissue begins to cease, as Weli as the Vascular netWork, and the mediey of vesicular substance observabie in the last coni: it is the reason also that Other conis succeed Whicli are delicate and analogous to the former, and that in the place of visibio celis and initiaments of gland 8 there exist a porosity and invisibio pollen. When LeeuWeuhoeli dissected off the exqui-Sitely thin, inner membrane Os an artery, and submitted it tothe microscope, he perceived, to his admiration, that it consistud of an incredibio number of Wonderfully minute paris runningone through the other, and nil connected together in the man- Der of a netWork; and wheu he separated and examinest theother part of the tunic that the former had covered, he foundiis fibres strotching round the artery n. 125 . Heuce it sol-lows that,

144. Membranes fewer in number and more simple incloseund convey the purer blood. Namely, the nerVeO-m Olive membrano, anil also the inmost, Whicli is successively attenuaten. 145. And one simple membrane in lases and conveys the spiri-

tuous suid; namely the inmost and most univerSal membrane, Whicli interiorly investing and accompanying the internat carotids, and having laid aside the muscular coat, and in the place

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os the vascular naid cellular membrane liming nequirod membranous conis Dom the dura and pia mater, penetrateS QVeuinto the cortical and cineritious substance of the brain, thoncointo the medullary substance and first beginnings of the ner- votis fibros, in Whicli is enclosed the spirituous fluid, Whicli is conveyed Within a simple superficies. 146. Consequently in the vesset' considored as signis ying both the continent and the content, or the membrane together With tho blood,) equully as in the blood and membranes, there arethree deorees of composition to be taken into consideration, ali ofwhich should be distinetly perceived. The vesseis of the sirsi δε-

blood-vesseis. The fame fact is attested by the exquisitely rosyskin os insanis; by the lurid and pale si in os old men; and by tho immense fide os insensibio and sensibie effluvia Whicli are expired Dom the system and inhaled into it; by the very structure of the cuticle and opinermis itself; by iis sensation and that of the other organs; by the privation Os sensation ariSing 1 rom loss of blood; by the transition os blood into the ex

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perspiration, Whicli is thus succinctly and ably described by

Oerlinave : There are Other exhalant vesseis under the litile Scales of the epidermis, Opening Obliquely, and of such exceed ing sinen ess, that LeeuWenhoeli rections that 125,000 of themopen in a Space that may be covered by a single grain of Sand. By these vesseis a most subtile liumor is constantly transpiringsrom every pOint of the body. . . . The exhalation Of this humoris carried On by the Whole externat epidermis, as Woli as by thecutiele of the mouili, the nares, the fauces, the larynx, thelungs, the ceSophagus, the Stomach, the infestines, the bladde and the uterus : hence iis quantity is greater than that of allthe other excretions put together. In faci, in the climate os Italy, in a person in the prime of life, Who enjoys easy circumstanees and tines moderate laod, the perspiration Whicli exhales Dom the externat shin, the mouth, and the nares, is equat iuwoight to sive eighths of the aliment tinen into the body.V Inst. Med., Π. 426, 427.) It necessarily folloWs, therelare, that this immense crowd and mediey of most subtile aliments are as truly conveyed through exSanguious VeSSels by R COntinuod passage in to the bl ood, as that they are asterWard carriodnWay Out Os it. 147. In the third ordor of vesseis are rankod tho fibriis of the nerves, but they stre nos in succession With vesseis of the Second degree, EXCept in the cerebrum, cerebellum, medulla oblongata, and medulla spinalis. This you Will see confirmest by numerous evidetices in Pari III., on the Corticul und Medullary Substance of the Brain. Τhis substance, called thecortical substance, is intermediate betWeen the vesseis of theblood und tho medullary sibres. For on the one haud it mnintains a relation to the arteries, On the Other to the fibres, and thus it assords a means of transition froin the one to the other by continuing the fluid of one into the other. Consequently it isthrough the modium of this substance that the blood acts uponthe organism of the brain, and vice versa; Or that the assections

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of tho brain and thoso of the rest of the body have communication vitii euch other. There re, by the laW of continuity, a

fibro is a vesset os a superior degree, or a VeSSel by Way ofeminen Ce, in the fame manner as the spirituous suid is biood by Way of eminence. Τhus are there three Orders of Vesseis,

according to the proposition. I 48. In conformity with these various degrees of veraeis, thecireulation iiself is subtriplicate: namely, 'st, a less univer8alcirculation, which is that of the red blood; second*, a more universat circulation, which is that of the purer blood; and third , a most universat circulation, which is that of the spirituous suid.

Not that there are three separate and preestablished circulations, but the fame circulation continuod into three, subordinaten one to the other, so that in respeet to iis operations and mode One is more universia than the Other. They are thus distinct Dom each other, While at the fame time, being connected, they have a mutuat relation one to the ollior, liko that of the cause to the thing caused, the prior to the poSterior, the Superior to the inferior. I spua nos here of the circuits of theother humors, as enumeraled by Nuch, Such as the saliva, gaStric juice, pancreatic juice, bile, lymph, &c., since their circuits are but species and particular, and are dependent upon that of the blood. For the gyre of the spirituous suid producesitself into the gyre of the purer blood, and the gyre of the

puror blood into that of the red blood; Whence there arises and lives, by an eternat copula and infinite circle, a unanimous harmony betWeen the circulations, Whicli are nevertheless persectly distinct. This brings to light the reason sor Whicli tho bloodacis as it Were in the ossice of a triumvirate, or sor Whicli it is os a threesold Origin, ordor, nature, and compoSition. In fine, Wehere see the reason of the severat Statemenis made in the preceding ch ter. Τhis circle, hoWever, We design to considerstili farther. 149. While the red blood is passing from veneis of iis ownorder into vesseis of another order, it hecomes divided into the purer blood, or into blood of the second order; the Saline, urinou8, or sulphurous atoms which had enlered into the composition of that depree, belv deposited at the mouths of inpress or division. Thisis a continuous effect Of the cause; an effect evinced by the con-

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glomeration and conglobation os the vostolos; likewise by the

Secretions in the extremities of the vesseis, such as prevail in allthe gland s and muscies, Whether they are in the mouth, fauces, gullet, Stomach, intestines, mesentery; Or in the Spleen, PRΠ- creas, and liver; or in the lungs, bronchia, and trachea; or in the bruitis and their medullae; or in the si in universally; OreSOCVer any pinguedinous, Oily, lymphatic, volatile humor chargod With ossiuvia, is mei With. I 50. A correspondino operation is carried on when the blood pa88ω from vesseis of the seconii order into vesseis of the strat, orinto the sbres. Such, for instance, as those in the cerebrum, cerebellum, medulla Oblongata and medulla spinalis, Whicli arethe nativo solarces of the fibres and of the three fluids, and where a discerption and division of the purer blood is carriod On, similar to that of the rod blood, bosore it passos into iis hioercircuit. Τhis biood, in Order to become spirituous fluid, mustbe retensed Dom the ethereat elements that temper, copulate, determine, and perfeci it. n. 9I, 92, kc.) These atomS, Whenthus liberaled, present themselves under the s Orm Os an oleagi-DOus moisture. That sueti a moisture is to bo sound in thoabove natat regions, is proved by the eXperienee Os numerousserSOΠS; at preSent, hoWever, I shali reser only to that of Ρacchioni. Besidos, says he, What shali I think of tho oleaginous lymph that is found bot voen the pia mater and the fortu- Ous and deep convolutions of the bruin y Can it bo supplied by the cortical glandes of the cerebrum and cerebellum 3 Νo; soris thesu bu Wiped dry, you Will not find any further humor pro-

Ceeding DOm them . . . . But On the Other hand, the Whole inuersursace of the pia mater, is Viped dry, is alWays spontaneouStymoistened, and is cOvered throughout With a Whilist, mucus, although it be separated Dom the dura mater aud cortex cerebri; Wheresore it seems impossibi e not to acknowledge in the porosities and lymphaties of the pia mater, the frue sOurces of this undant humor. . . . On this subjeci, Vallisnerius not long ago remindod me of an observation mado by the diligent Rub sch, to the effect that the pia mater . . . is in various places enriched

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iise or the fluid proper to them, is a circumstance Whicli miratbe demonstrated by a variety of proose, mere I at liberty to eX-tend this argument boyond the limit of tho facts Whicli preface

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intercostat arteries, in the branches of the agygos, and in ali theother arteries and vetus; that euch vcsset is encompassed Withmotive circles, no motive fibre of Whicli is Without a nervous fibre. Consequently the One only force and substance proper ton muscle, is a vesset thus fibraled; that is to say, the larce audSubstanee proper to a muscle is a nervous fibre. There is One particular experiment of Lancisi Whicli illustrates the prosent

153. It is stated, secondiy, that When the vesseis are thus Woddon to the fibro, the fibros infuso luto the vesseis their oWngeniat spirit. This follows Dom the former statement, Since itis in the vesseis that ali the fibres have their termination, and that the blood experiences a vivification ut every potnt of iis progression. For this reasOn the most universat tunic Whichascends into the order of the simple fibre sn. 137) is the inmost, and subtendes in the arteries the motive rings, for the purpOSeos immediately transuding a perpetuat deW. The author last referrest to describes this innermost membrane as containing Only the most minute foramina,'' and says that being madeup of a most dense tissue os villi, it alone confines the more

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154. Such is the manner in which it performa iis universalcircle, netther the beyinnino nor the end of which is determinabie, but by means of which there is nothino that the blood, in iis oron

limited universe, Ges not continue, supply with moisture, risuriSh, renovate, form, actuale, and vivito. The nature of the continuityos the circulation of the fluids, and of the expansion os thesolids or vesseis, both the circulation and expansion being alitio perpetuat,) is clear DOm the Statemenis atready made. Butalthough a universat circle Would seem to be Without beginning

one degree and that of another, Whicli serve to Ward osy the redblood in iis undivided state, and prevent it Dom mahing, by a

Continuous current, an irruption into the circle of blood osanother Order. Similar precautions are talien to preVent au

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Observations he is convinced, that in an area no largor than thatos a finger-nail, there are more than a thousand distinet currenis Or circulis' n. 125 . That there are litile stations orinternodia of this hiud in the body, can be very clearly proved om the cortical and cineritious substance of the bratus, Whichis intermediato belweon the smad blo0d-vesseis and the fibres, and from Whicli Ue may argue the existence of similar smali stations Or internodia in the body. Consequently We shali revert to this subjeci aster We have sirst treated of the nature of

connected With oach othor by mutuat superposition ; and that in the samo Ordor in Whicli tho blood is divided they are purifled